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kto434

Kohler M12 replace K301?

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kto434

Guys, I need your help/advice.  I have a C-121 with a broke Kohler K301 (needs rebuilt).  I have a nice running Kohler M12.  Will the M12 fit without all sorts of hood, PTO, muffler, etc. alteration?  Thanks!

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953 nut

Probably the biggest change will be the routing of the choke and throttle cables. Most everything else should line right up. Most K-301s are  battery ignition and most M-12s are Magneto ignition so you will probably have to get a new ignition switch and do a bit of rewiring if this is the case.

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kto434

OK, thanks so much for your comments--they help!  Looks like I have a Saturday project ahead of me.

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Elkskin's mower junkyard
4 hours ago, kto434 said:

OK, thanks so much for your comments--they help!  Looks like I have a Saturday project ahead of me.

its really easy. i put a m8 on my dads 62 502 wheel horse. he loves the m8.

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gwest_ca

The simplest way to modify the ignition would be to add a relay to the M ignition wire.

The relay would normally ground the ignition to shut the engine off.

With the original battery ignition switch in the run position it would open the relay contacts and allow the engine to run.

Doing it this way makes use of the original safety switches that control the ignition as they are presently wired.

A very common relay

Garry

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953 nut
52 minutes ago, gwest_ca said:

The relay would normally ground the ignition to shut the engine off.

With the original battery ignition switch in the run position it would open the relay contacts and allow the engine to run.

Doing it this way makes use of the original safety switches that control the ignition as they are presently wired.

Garry, you continue to amaze me. The solutions you share on this site are fantastic! 

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gwest_ca

This is something Wheel Horse did starting in 1980. The C-Series with battery ignition and B-Series with magneto ignition used the same 103990 battery type of ignition switch. The B-Series have what they named a kill relay added to control the ignition and utilized the very same safety switches and wiring. A brilliant solution.

 

Garry

Tractor 1980-81 B-Series Wiring detailed SS.jpg

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gwest_ca

Here is a relay we can get here in Canada at Princess Auto that comes with a wired socket. Once it is installed it is plug and play. No more wondering where that loose wire came from. Northern Tool carries many of the same products PA does.

 

Garry

PA 8402034 30 amp relay & socket.jpg

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953 nut
12 minutes ago, gwest_ca said:

starting in 1980. The C-Series with battery ignition and B-Series with magneto ignition used the same 103990 battery type of ignition switch. The B-Series have what they named a kill relay added to control the ignition and utilized the very same safety switches and wiring. A brilliant solution.

Thanks, we will all have to keep that in mind. So frequently we have questions about changing out switches and have told people they NEED an "M" switch for the Magnum engines and an "I" switch for the "K" with a coil. I had never heard of this before and will keep it in mind.

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gwest_ca

This thread has been about replacing an engine with battery ignition for one with magneto ignition and the required changes.

 

The following statement is not correct if using the 103991 magneto ignition switch to control battery ignition.

The same relay will work for an engine swap the other way - magneto ignition to battery ignition. Wired slightly different with the power supply to the relay fused.

 

Garry

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953 nut
5 hours ago, gwest_ca said:

The same relay will work for an engine swap the other way

I was thinking the same thing, that allows the safety switches to be retained as is.  :thanks:

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clueless

Garry, This looks like just what I need. As some of you know electrical is definitely not my strength thus the "clueless". I have a C81 and a B80 and a brand new Kohler M8. I plan to put the M8 in one of them. They are both battery ignitions. The M8 is a mag ignition. The M8 has only 3 wires and one is the spark plug wire. The other two are violet and white. I know the white comes from the mag and the violet from the regulator. Thought I would have to change out the ignition switch. This looks like the best way to go. I just need some more explanation as to how to wire the M8 with this and do I keep the starter wiring the same? Please talk slow as I am the poster child for ADD and tend to need detailed explanations. A nice colored diagram would certainly help. Thanks. Chris

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pfrederi

With only  white wire and a violet wire I would summize your M8 has the unregulated 3 amp charging system (could the violet be dark blue..that would be the magneto kill wire).  This will not be quite as straight forward.

 

What is the spec number of your M8

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clueless
38 minutes ago, pfrederi said:

With only  white wire and a violet wire I would summize your M8 has the unregulated 3 amp charging system (could the violet be dark blue..that would be the magneto kill wire).  This will not be quite as straight forward.

 

What is the spec number of your M8

The engine has the regulator bolted to the blower housing. The violet wire is coming from the regulator, the white wire is from the mag and the violet wire goes to the B on the switch. The same set up as my 1989 312 with the mag engine. The M8 spec number is 301615, it was a replacement for a cushman, what cushman I don't know.

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pfrederi

That makes it easier then.  I know this thread has a good idea about using a relay for the kill...

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oldredrider

One other item to be addressed is the C-121 is a cradle mount motor. Is the M12 a cradle or flat base motor? New mounting holes may need to be drilled in the frame. Also, belt guard and PTO hoop may need to be changed if the M12 is a flat pan model. 

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kto434

Wow, thanks so much--great advice/tips--they really help!

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